Electrokinetic Remediation of a Heavy Metal-Contaminated Soil and its Effect on Microbial Biomass-C and on Microbial Coefficient

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Use of electrokinetic technique for remediation of contaminated soils has recently been highly attended to, but there are still concerns regarding the effect of this process on soil microbial activity. In this study, changes in concentration of heavy metals extractable through 4N nitric acid, microbial biomass-C, and microbial coefficient, following electrokinetic remediation of a native soil contaminated with heavy metals (zinc, lead, nickel and cadmium) in and at a pilot-scale were evaluated. After 20 days of soil being imposed to a constant voltage gradient of 0.83 Vcm-1 of soil column, the results revealed that over 30 percent of heavy metals close to the anode were removed. However, removal of metals from a distance of 24 cm from cathode about some of the metals (cadmium and lead) is negative. The effect of electrokinetic remediation on biological parameters showed that the level of microbial biomass-C as well as microbial coefficient (following the electrokinetic process) decreased significantly (p< 0.01) with the highest reduction being observed near the cathode where heavy metals had been accumulated. A lack of pH control and its rising trend from anode towards the cathode has most negatively affected the process.

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